uxcell 5mm to 8mm Shaft Coupling 30mm Length 25mm Diameter Stepper Motor Coupler Aluminum Alloy Joint Connector for 3D Printer CNC Machine DIY Encoder https://www.amazon.com/dp/B06X9WY3C3/ref=cm_sw_r_cp_apa_i_tGRKCbSFYKNPA

If you have Amazon prime ID recommend a replacement like this style.